Some K-drama actors have mastered certain roles so perfectly that it’s hard to imagine anyone else playing them. There are times when an actor ends up portraying a similar type of character more than once. Over time, these performances become a defining part of their filmography, with fans instantly associating them with that particular persona. We spotlight five actors who have consistently excelled at playing a similar role multiple times.

To the delight of longtime fans—spoiler alert—the cast of Hospital Playlist made special appearances throughout Resident Playbook, both individually and as couples. In honor of this expanding universe, we’re ranking our six favorite couples from Hospital Playlist to Resident Playbook.

7 Medical Dramas to Watch If You Loved "Trauma Code: Heroes on Call" — Prepare for More Drama!